Journal of Northeastern University(Natural Science)

Robot Zero Calibration Method and Accuracy Evaluation for Spatial Parameter Clustering Identification

ZHAO Bin， WU Cheng-dong， JIANG Yang， SUN Ruo-huai

2023, 44 (6): 761-769. DOI: 10.12068/j.issn.1005-3026.2023.06.001

Abstract ( 693 )

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The paper proposes a robot zero calibration device and method based on spatial parameter clustering identification to overcome the shortcomings of traditional shaft pin and laser tracker calibration. The dial indicator and spatial analytic geometry are used to construct the zero calibration equation， which analyzes the robot’s theoretical post and posture values to obtain the zero-position training parameters. The clustering module identifies multiple sets of zero-position training parameters， and the optimal zero-position parameters of each joint can be solved. The experimental results show that spatial parameter clustering can improve the absolute accuracy by 72.9%， compared to the most commonly used shaft pin calibration method. Compared with the laser tracker calibration method with the highest accuracy， the time efficiency is improved by 87.5%. This method considers the calibration accuracy and efficiency and significantly improves the adaptability to the calibration environment.

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An Efficient DBG Indexing Method for Large-Scale Read Mapping

YU Chang-yong， LI Jun-jie， MA Hai-tao， ZHAO Yu-hai

2023, 44 (6): 770-776. DOI: 10.12068/j.issn.1005-3026.2023.06.002

Abstract ( 510 )

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In order to answer two questions about de Bruijn graph(DBG) in bioinformatics: ① For any k-mer， answer whether it is the vertex of DBG; ② For any vertex of DBG， answer its adjacency information(incoming edge and outgoing edge)， an efficient DBG indexing method for large-scale read mapping is proposed. In this paper， the above two questions are transformed into the exact finding problem of k-mer and (k+1)-mer on non-repetitive multipath， and are solved by using FM-index. Firstly， a given reference sequence is compressed， which is the discovery of non-repetitive multipaths， thereby compressing the presence of large-scale repetitive (k+1)-mers in the sequence. Secondly， the DBG is indexed based on the non-repetitive multipath FM-index. The k-mer is searched whether it appears on the DBG， and if so， the direct predecessor and direct successor nodes of the k-mer are provided to improve the spatial-temporal efficiency. Finally， experiments are performed on the genomes of 62 E. coli strains. The experimental results show that the method proposed can efficiently index the DBG of multi-reference sequences.

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Effect of Heat Treatment on Microstructure and Mechanical Properties of Super Austenitic Stainless Steel Clad Plate

WANG Ming-kun， LUO Zong-an， ZENG Zhou-yu， XIE Guang-ming

2023, 44 (6): 777-783. DOI: 10.12068/j.issn.1005-3026.2023.06.003

Abstract ( 535 )

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The N08367/Q345R super austenitic stainless steel clad plate was prepared in vacuum rolling cladding process， and the effects of hot-rolling， quenching and tempering processes on its microstructure and mechanical property were analyzed. The results show that the decarburization layers of the carbon steel substrate increased significantly after heat treatment. In quenching process， the diffusion of the C element led to the precipitations of χ phase and intergranular carbides， while the metastable χ phase could be decomposed into more intergranular carbides after tempering process. An obvious interfacial martensite zone was formed by the interfacial diffusion of Cr， Ni， Mo and C elements. After tempering， the residual stress at the interface was reduced and the martensite at the interface was transformed into the tempered martensite. The nucleation， growth and recrystallization of new grains at the interface occurred at the 650℃ tempering， resulting in the formation of grains with the same orientation as the grains of substrates at the interface. The interfacial shear strengths of all samples were above 350MPa. The strength， plasticity and toughness of the substrate material of the clad plate tempered at 650℃ can meet national standard requirements.

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Preparation of Nano-sized MgO Using Electrolytic Mg(OH)₂

GUO Li-li， TU Gan-feng， FENG Nai-xiang， DI Yue-zhong

2023, 44 (6): 783-789. DOI: 10.12068/j.issn.1005-3026.2023.06.004

Abstract ( 543 )

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The precursor of Mg(OH)₂ was prepared by diaphragm electrolysis with bischofite in salt lake， and then calcined to obtain nano-sized MgO， so as to realize the high-quality utilization of waste resources. The pyrolysis kinetics of the calcination process of Mg(OH)₂ was analyzed and the effects of calcination conditions on the MgO properties were investigated， combined with the pyrolysis mechanism and rate. The results show that with increasing calcination temperature， the specific surface area of MgO decreases， the activity firstly increases and then decreases， and the grain size increases. When the calcination time increases， the specific surface area and activity of MgO decreases， the grain size increases， and the structure becomes denser. Furthermore， with the increase of heating rate， the specific surface area and activity of MgO firstly increases and then becomes stable， and the grain size mainly remains unchanged. The maximum specific surface area of MgO is 29.3m²/g， the minimum CAA is 66s， and the minimum grain size is 27.8nm.

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Theoretical and Experimental Research of BNES in Torsional Vibration Suppression of Rotor Systems

DOU Jin-xin， YAO Hong-liang， CAO Yan-bo， GUO Yu-liang

2023, 44 (6): 790-798. DOI: 10.12068/j.issn.1005-3026.2023.06.005

Abstract ( 533 )

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A bi-stable nonlinear energy sink(BNES) is proposed to suppress the torsional vibration of rotor systems. Firstly， the structure and working principles of BNES are introduced， and the dynamic equation of the rotor-BNES system is established. Then， the vibration suppression performance of BNES under transient and steady-state excitation is studied by the numerical calculation method， and compared with the linear dynamic vibration absorber(LDVA) with the same moment of inertia. Finally， a test platform is built to verify the capacity of BNES to suppress the torsional vibration of the rotor system. It is shown that the proposed BNES has a good vibration suppression effect on the transient response and steady-state response of the rotor system， and under the given parameters， the vibration suppression performance of BNES is better than that of LDVA.

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Research on Robotic Grasping Detection Based on Improved Cascade R-CNN Model

JIANG Yang， ZHAO Feng-yu， CHEN Xiao

2023, 44 (6): 799-807. DOI: 10.12068/j.issn.1005-3026.2023.06.006

Abstract ( 393 )

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In order to improve the grasping detection accuracy of the multi-object grasping detection network， a robotic arm grasping detection algorithm based on the improved Cascade R-CNN model is proposed. Firstly， the introduction of the ResNeXt structure can improve the accuracy of the model without increasing the difficulty of network design. The atrous spatial pyramid pooling module is introduced to solve the problem of low resolution. Then， the grasping box regression branch and the angle classification branch are optimized by the divide and conquer method. Secondly， aiming at the lack of multi-object grasping datasets， a multi-object grasping dataset (MOGD) is constructed， which effectively expands the multi-object grasping detection dataset. Finally， a grasping detection network is designed based on the improved Cascade R-CNN model. The experimental results show that the improved algorithm is more efficient. The experimental accuracy of the PI-Cascade R-CNN is 93 %， which is 1.5 percentage higher than that of the Cascade R-CNN.

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Research on Temperature Uniformity of Gear Moving Induction Heating

ZHAO Yu-qian， WANG Shan， WEN Huai-yu， HAN Yi

2023, 44 (6): 808-816. DOI: 10.12068/j.issn.1005-3026.2023.06.007

Abstract ( 361 )

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Due to the huge volume， complex structure and end effect of wind power gear， it is difficult to realize the uniform heating of tooth profile and tooth width， which affects the final strengthening quality. In this paper， the average temperature， the maximum temperature difference and the relative temperature fluctuation rate are taken as the evaluation indexes of the heating effect. The temperature fields along the tooth profile and the tooth width direction of wind power gear in the scanning induction heating process are studied， and the phase transformation and hardening of the gear are analyzed. It is found that the temperature uniformity increases gradually in the direction of tooth width from top to bottom within a certain range， which is due to the drastic change of tooth structure thickness. To gears strengthened by induction hardening in steady-state positions， the depth of hardened layer in the direction of tooth profile is almost the same as the depth of macroscopic phase change layer， and the transition region is relatively narrow. The heating effect and strengthening result of gear scanning induction heating are expounded， which provides the research foundation for the wide application of high-performance steel materials in the field of wind power.

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Design of a Single Excitation Three-Dimensional Vibration Cutting Device for Improving 304 Stainless Steel Machined Surface

LIU Xiao-han， ZOU Ping， QU Yuan-hui， FANG Li-ting

2023, 44 (6): 816-823. DOI: 10.12068/j.issn.1005-3026.2023.06.008

Abstract ( 427 )

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In order to solve the problems of poor surface quality and easy to produce burrs in the traditional forming process of 304 stainless steel，a new type of three-dimensional ultrasonic vibration cutting device was designed and tested. Firstly，through the analysis of the geometric deformation relationship of the device structure，the theoretical motion trajectory model of the tool tip is established. The trajectory model is fitted by Matlab and the actual output trajectory is simulated by ANSYS. The tool tip motion trajectory is a three-dimensional parabola in space. Secondly，the cutting experiment with or without ultrasonic vibration was carried out on the device， and the machined workpiece surface was measured and observed by the super depth of field system and the three-dimensional profiler. It was found that the arithmetic average height of the machined surface roughness under ultrasonic vibration cutting is significantly lower than that of the ordinary turning. The results show that ultrasonic vibration cutting has better machinability for 304 stainless steel than conventional turning.

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Remaining Useful Life Prediction of Cutting Tools Based on SFS-SVR in High Speed Milling Operations

HUANG Xian-zhen， SUN Liang-shi， GAO Wei， LI Yu-xiong

2023, 44 (6): 824-831. DOI: 10.12068/j.issn.1005-3026.2023.06.009

Abstract ( 473 )

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In high speed milling operations， it is urgent to accurately predict the remaining useful life of cutting tools to determine the best time to replace them， but there is often a problem of insufficient historical data in the prediction. Therefore， a method for remaining useful life prediction of cutting tools in small sample space is proposed， which is based on the support vector regression (SVR) method. And the stochastic fractal search (SFS) algorithm is used to optimize the key parameters of SVR. Compared with the traditional method， it obtains better model parameters and faster convergence speed. Finally， the as-adopted method is compared with the hidden Markov model (HMM) approach. The accuracy rate increases from 0.6277 to 0.8199， which provides a reliable reference for tool replacement.

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Light Environment Evaluation of Cargo Ship Cockpit for Night Tasks

SUN Yi-wei， CHEN Deng-kai， GAO Xin-wei， LIU Jia-xuan

2023, 44 (6): 832-839. DOI: 10.12068/j.issn.1005-3026.2023.06.010

Abstract ( 448 )

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During night driving， the light source in the cockpit comes from electronic screens， and the brightness has a direct impact on the drivers visual ergonomics. Based on the characteristics of the cargo ship cockpit light environment during night driving， the performance of participants under different screen brightness is analyzed through dark environment experiments. From the perspective of task effectiveness， the light environment of the cargo ship cockpit is evaluated based on three dimensions of cognitive efficiency， dark adaptability， and comfort. The experimental data is fitted to construct a light environment evaluation model of the cargo ship cockpit for night tasks. And it is concluded that the task performed well when the screen brightness value is controlled at 20cd/m². It plays a guiding role in the optimization of the light environment of the cockpit during cargo ship night driving.

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Global Power Matching of Concrete Pump Truck Based on Advanced Particle Swarm Optimization Algorithm

RAO Hong-yan， WANG Shao-jie， HOU Liang， SU De-ying

2023, 44 (6): 840-848. DOI: 10.12068/j.issn.1005-3026.2023.06.011

Abstract ( 336 )

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The optimization algorithm of concrete pump truck global power matching technology has poor solution quality， this paper proposed a condition adaptive global power matching strategy based on advanced particle swarm optimization. Firstly， based on the characteristic data of engine and hydraulic pump， a pumping system model on MWorks that integrated five major modules of hydraulic， mechanical， control， load and power is builted; Then， the advanced particle swarm optimization algorithm is used for global matching optimization and output the economic matching value of parameters under different operation requirements; Finally， a pumping system simulation platform is established to analyze the energy-saving effect of different power matching strategies under typical conditions. The results show that compared with the traditional strategy， strategy proposed saves fuel by 5.86%，5.24% and 1.74% under light， medium and heavy operation， respectively.

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Research on Magnesioferrite Growth in the Mixed Melting System of Low-Iron Red Mud

HUANG Fei， WANG Xin-yu， WEN Xin-yu， CHANG Zhuo-ya

2023, 44 (6): 849-856. DOI: 10.12068/j.issn.1005-3026.2023.06.012

Abstract ( 468 )

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The SiO₂-Al₂O₃-CaO-MgO-Fe₂O₃ multi-mixed melting system was constructed using low-iron red mud， and the magnesioferrite crystalline glaze was prepared by a high-temperature phase reconstruction method. The crystal growth behavior of magnesioferrite at different temperatures was observed through X-ray diffraction and field emission scanning electron microscope. The results show that the increase of sintering temperature is helpful to the growth of magnesioferrite crystal， which has an autogenous-semi-autogenous granular structure.The sample has the best resistance against acid and alkali after 96h with a mass-loss rate less than 0.1% under a sintering temperature of 1270℃. In addition， its wear rate is 1.4×10^-5mm³/(N·m)， and its Vickers hardness is 8.68GPa， which meets the performance requirements of daily ceramic glazes.

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Influence of the Inlet Flow Rate on Flow Field Evolution and Mineral Particle Distribution in the First Turn of Spiral Separators

MENG Ling-guo， GAO Shu-ling， ZHOU Xiao-hong， WEI De-zhou

2023, 44 (6): 856-862. DOI: 10.12068/j.issn.1005-3026.2023.06.013

Abstract ( 319 )

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The characteristics and evolution of the flow field in the first turn of the spiral separator play an important role on the movement and separation of mineral particles. For the laboratory-scale spiral separator(300mm)， the turbulence model of RNG k-ε and the multiphase flow model of the volume of fraction(VOF) as well as the Eulerian Multi-fluid VOF were used to investigate the influence of the inlet flow rate on the flow field evolution and the distribution of hematite and quartz particles in the first turn of spiral separators. With the increase of inlet flow rate， the distance to reach the stability of the flow film shape， primary and secondary flows at the outer trough are prolonged. The stratification performance of quartz and hematite is enhanced. Meanwhile， the hematite ore band is correspondingly widened， and the migration of quartz to the outer trough of the thick flow film region is increased. With the increase of the inlet flow rate， the maximum separation efficiency of the first turn increases first and then gets stable. The suitable inlet flow rate of 7L/min can be obtained with the maximum separation efficiency of 61.45%.

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Experimental Study on Acid Resistance of PCT Fiber

CHANG De-qiang， CHEN Lei， MAO Ning， LIU Jing-xian

2023, 44 (6): 863-870. DOI: 10.12068/j.issn.1005-3026.2023.06.014

Abstract ( 357 )

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To understand the effect of acid solution treatment on poly 1，4-cyclohexylen dimethylene terephthalate(PCT) fiber， the surface morphology， mechanical properties， aging reaction activation energy and infrared spectrum of PCT fibers before and after sulfuric acid and nitric acid treatment were tested and analyzed by scanning electron microscope(SEM)， single fiber strength machine， synchronous thermal analyzer(STA) and Fourier transform infrared spectrometer(FTIR). The results show that the acid immersion treatment can cause the shrinkage of PCT fiber， leading to the surface corrosion of the fibers and the occurrence of dents and cracks; The entering of water molecules into the fiber macromolecule gap of PCT fiber causes a simultaneous decrease in breaking strength and elongation at break; The breaking strength of PCT fiber decreased with the increase of acid solution concentration， treatment time and treatment temperature; Unless at a lower concentration and temperature， the sulfuric acid resistance of PCT fiber is better than that of nitric acid; The sulfuric acid resistance of PCT fiber is weaker than that of the polyphenylene sulfide(PPS) and the polytetrafluoroethylene(PTFE) fiber， and better than that of the polyimide(PI) and the Aramid 1313 fiber; Acid solution treatment can lead to a decrease in the activation energy of the aging reaction and molecular stability of PCT fiber.

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Green Innovation and Pricing Decisions in an E-commerce Closed-Loop Supply Chain Under the Subsidy Policy

GUAN Zhi-min， ZHAO Ying， MOU Yu-xia， YE Tong

2023, 44 (6): 871-879. DOI: 10.12068/j.issn.1005-3026.2023.06.015

Abstract ( 447 )

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An e-commerce closed-loop supply chain game model under the subsidy policy was constructed based on different cooperation models of partial authorization， full delegation and two-way competition. The key factors for manufacturers to engage in product green innovation were explored and the impact of government subsidies and innovation cost factors on product green innovation and pricing decisions was analyzed. It was shown that manufacturers make green innovation only when government subsidies or cost savings from green innovation are large enough. Government subsidies and manufacturers’ willingness to make green innovation are the highest under the partial authorization model. In contrast， government subsidies are the lowest under the two-way competition model and manufacturers’ willingness to make green innovation is the lowest under the full delegation model. Green innovation under the subsidy policy can reduce the selling price， increase the recycling price， and significantly improve manufacturers’ profit.

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Platforms’ Selection Strategies of Sales Contracts and Logistics Modes Considering Product Quality Decision

MA Yong， ZHANG Cui-hua

2023, 44 (6): 880-888. DOI: 10.12068/j.issn.1005-3026.2023.06.016

Abstract ( 326 )

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Considering manufacturers’ quality decision， the optimal combination between sales contracts and logistics modes for e-commerce platforms is explored. Based on platforms’ operational realities， and taking both sales contracts(direct selling contract and reselling contract) and logistics modes(outsourcing and self-logistics) into account， four combination strategies are constructed: direct selling and outsourcing(strategy DO)， direct selling and self-logistics(strategy DS)， reselling and outsourcing(strategy RO) and reselling and self-logistics(strategy RS). By formulating sequential game models and deriving optimal quality， retail prices and logistics service efforts decisions， the equilibrium results under each format are conducted; further， the impacts of logistics service modes and sales contracts on quality decision are explored. The results show that regardless of which sales contract is chosen， platforms tend to provide delivery services by themselves rather than outsourcing that to TPLS (third-party logistic suppliers). Since providing delivery service by platforms not only benefits both parties but also motivates manufacturers to improve products quality and lower selling prices. Platforms’ optimal combination strategy is closely related to the commission rate， and if the rate is below a certain threshold that is positively related to the quality cost coefficient of products， the optimal strategy is DS; otherwise， the optimal choice is RS.

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Hierarchical Dimensionless Method Based on Data Distribution Characteristics and Its Equilibrium Analysis

YI Ping-tao， YUAN Jian-rong， LI Wei-wei

2023, 44 (6): 889-897. DOI: 10.12068/j.issn.1005-3026.2023.06.017

Abstract ( 354 )

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The hierarchical dimensionless method can effectively remove the effect of different index dimensions， and solve imbalanced data distribution and low discrimination caused by anomalous index values. However， when using this method， it is necessary to artificially specify the number of partition intervals so that the dimensionless results are interfered by human factors and lose objectivity. To solve this problem， a dimensionless method of density hierarchy is proposed considering the distribution characteristics of raw data. This method divides the interval according to the density of data distribution， objectively determines the hierarchical series， and takes into account the advantages of the hierarchical dimensionless method. The calculation is comparatively simple and reduces human factors. In addition， through the stochastic simulation method， it is found that the method has good anti-interference to outliers， and the balance of dimensionless results is affected by the scale of raw data.

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Cross-Industry Risk Contagion Effect in China’s Stock Market During Crises

YU Jin-ming， JIN Xiu， LIU Yue-li

2023, 44 (6): 898-906. DOI: 10.12068/j.issn.1005-3026.2023.06.018

Abstract ( 401 )

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In the context of frequent crisis episodes， the R-Vine Copula and the spillover index model are applied to study the cross-industry risk contagion effect in China’s stock market from the dual perspective of risk linkage and risk spillover through combing major crises such as the financial crisis， the European sovereign debt crisis， and the COVID-19 epidemic. The results show that cross-industry contagion occurs in China’s stock market during crises. The changes of industry linkage network and spillover network are characterized as being event-driven. During crises， industrial is always at the center of the linkage network with consumer discretionary and materials being closely linked to industrial at all times. They are the main risk-driven industries. Energy， telecommunication， medicine， and finance are always at the margin of the linkage network as the major risk-accepting industries. The results provide meaningful references for investors’ micro-asset allocation and regulatory authorities’ macro-prudential management and risk prevention.

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Study on Morphology of Red Blood Cell in Micro-channel Towards Vessel-on-Chip

HU Sheng， YE Jun-yan， ZHAO Yong

2023, 44 (6): 906-912. DOI: 10.12068/j.issn.1005-3026.2023.06.019

Abstract ( 437 )

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Red blood cell (RBC)， undertaking the significant work of oxygen transport to maintain human life， could shuttle spindly capillaries by their own stretching and contractile properties due to their biconcave discoid shape and hyperelastic responses. In this paper， the coupled fluid-solid module in finite element software COMSOL was used to study the dynamic simulation of RBC when the three factors， including capillary width， plasma viscosity， and blood flow rate were considered. The results implied that the RBC could easily pass through capillary with hole size of 3 μm， and the aqueous shear stress was 4.5 times greater than that in the capillary with 6 μm hole size. Meanwhile， the plasma viscosity of 5.5 mPa·s induced parachute-like formation of RBC. Furthermore， biconcave structure in the center gradually disappeared and turned into bulge along the flow direction. With regard to the study on fluidic velocities in T-shaped and Y-shaped micro-channel， both results indicated that the asymmetric structure caused the falcate shape of RBC. In addition， the higher fluidic velocity in the other branch channel， the easier the convergence leaded to the disappearance of falcate shape and the rod posture lying flat flowing in the solution.

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